AS integrated circuits, become faster and denser they become more sensitive to process variations. This is especially true in analog circuits employing complementary metal on silicon (CMOS) transistors, both field effect and bipolar. In such a case these circuits require component tracking for quality operation. As used herein component tracking means the matching of selected electrical characteristics of both active and passive devices in the circuit. For superior results, in integrated analog circuits, it is necessary the transistors track one another more closely than the manufacturing processes used to create them can provide.
Techniques for improving component tracking include physical abrasion of resistive deposits on the surface of the integrated circuit or by counter doping of selected regions as well as improved process controlling the making of these circuits. Most of these efforts have been found to be so expensive or time consuming or difficult as to be impracticable or cost prohibitive for use in manufacturing.
Accordingly it is desired that an inexpensive but highly accurate way of achieving such tracking of both active (e.g.,transistors) or passive (e.g., resistors) devices in integrated circuits be found.